The present invention relates generally to liquid crystal display devices; and, more particularly, the invention relates to a liquid crystal display device of the type employing the so-called lateral electric field scheme.
A liquid crystal display device of the so-called lateral electric field type is constructed so that a picture element, or “pixel”, electrode and an opposite, or “counter”, electrode are arranged to provide for creation of a generally horizontal electric field between this pixel electrode and the counter electrode in a pixel region on the liquid crystal-side surface of one substrate of a pair of substrates, which are disposed to oppose each other with a layer of liquid crystal material interposed therebetween. Thus, the liquid crystals are driven by certain components of the electric field which extend almost in parallel with the substrate.
One example of such an arrangement, as applied to an active matrix type device, is designed to provide as the pixel regions respective regions which are surrounded by a plurality of parallel-provided gate signal lines on or over the liquid crystal-side surface of one substrate and a plurality of drain signal lines that are provided in parallel in such a way as to cross or intersect these respective gate signal lines on the substrate. Within each of these pixel regions, there are a thin-film transistor, which is operative in response to a scanning signal received from a gate signal line, the pixel electrode to which an image or video signal is supplied through this thin-film transistor from a drain signal line, and the counter electrode to which a signal for use as a reference with respect to the image signal is supplied.
The pixel electrode and the counter electrode are each formed as a band-like or strip-shaped pattern which extends in one direction, wherein each of these electrodes is ordinarily arranged to be formed of two or more components, which are alternately disposed.
In this arrangement, the counter electrode is formed on or above the upper surface of a dielectric film, that is formed to also cover its associated drain signal line, while the center axis of the counter electrode is arranged to substantially coincide with the center axis of the drain signal line, although it has a greater width than that of the drain signal line. The purpose of this arranged of elements is to cause an electric flux line from the drain signal line to easily terminate at its overlying counter electrode, to thereby prevent termination at the pixel electrode. If the arrangement is otherwise, the electric flux line terminates at the pixel electrode, with the result that there will be an unwanted production of noise.
The counter electrode described above is formed at the upper surface of a dielectric film that is formed to cover the gate signal line also in such a manner that the counter electrode is integral with the counter voltage signal line, wherein a reference signal is to be supplied to each counter electrode through this counter voltage signal line.